1. Field
Various embodiments of the present disclosure relate to an illumination apparatus. In particular, certain embodiments relate to an illumination apparatus that uses a light emitting diode (LED), an organic light emitting diode (OLED), or the like as a light source.
2. Description of Related Art
Incandescent or fluorescent lights are commonly used for indoor or outdoor illumination. For street lights, sodium lamps or other metal lamps are arranged along the sides of a roadway with an interval of about 30 to 50 meters. Incandescent lights used as light sources for illumination purposes emit light by heating filaments, but have low efficiency. Fluorescent lights, on the other hand, emit light by illuminating fluorescent substances. While the fluorescent lights have an advantage of low power consumption over the incandescent lights, the fluorescent lights use mercury (Hg) as the fluorescent substances which is harmful to human body. Also, sodium lamps or other metal lamps have drawbacks of high power consumption and short lifespan.
Recently, illumination devices adopting LEDs or OLEDs as light sources have been developed. LED or OLED show excellent performance as lighting materials because they have longer lifespan and low power consumption. Specifically, LED or OLED lamps have a lifespan greater than three times of typical fluorescent lights with comparable brightness thereof.
The LED or OLED lamps, however, have limited usage for illumination due to their narrow viewing angles and heating problems. Therefore, there is a need to develop an LED or OLED lamps that obviate these problems.
Korean Patent Publication No. 2009-0041480, entitled “Lamp-Type LED Illumination Apparatus with Scattering Structure,” discloses an illumination apparatus that deals with the above-mentioned problems. The illumination apparatus disclosed in this publication includes a socket portion having a screw thread on its surface; an outer tubular body connected to the socket portion; a power source disposed inside the outer tubular body and electrically connected to the socket portion, the power source supplying power through power conversion, controlling the power supply, and managing heat dissipation; an outer scattering lens portion connected to the outer tubular body and scattering light; a heat pipe disposed inside the outer scattering lens portion to dissipate heat; and an LED device connected to the heat pipe through an electrical connection with the power source and emitting light by supplying and controlling power from the power supply. The illumination apparatus further includes a heat dissipater that dissipates the heat generated in heat pipes by the LED device.
The LED device includes a plurality of light modules which consist of light-emitting LEDs; a plurality of circuit boards each of which is connected to the respective one of the light modules; and a plurality of inner scattering lenses, each of which is connected to the respective one of the light modules to primarily scatter the light emitted from the LED modules.
In the above apparatus, a heat dissipater portion includes a heat dissipation plate having a plurality of pins that increase a heat dissipation contact area; and a heat dissipation fan being in contact with the heat dissipation plate and blowing wind in a direction perpendicular to its rotational direction, to externally discharge the heat generated from the plurality of light modules.
Further, the outer scattering lens portion is composed of a plurality of concave lenses having a hexagonal cross-sectional shape and being connected adjacent to each other. The outer scattering lens portion thus configured scatters, for the second time, the light that has been primarily scattered by the inner scattering lens portion. The scattered angle of the light emitted from the light modules is then increased, thereby enhancing light uniformity.
The illumination apparatus described above, however, has a problem of reduced heat dissipation efficiency due to the fact that the heat generated by the light modules is dissipated through the elongated heat pipes disposed inside the outer tubular body and that the multiple heat pipes are disposed in close proximity to one another. Furthermore, since the light modules are fixed and thus the degree of scattering of the emitted light is constant, it may be difficult to control the light uniformity in certain circumstances.